Various aspects of the ability of near-UV light to interfere with the normal functioning of the ocular tissues are being investigated. Mice are to be maintained in an environment of black light with a regimen of dietary supplementation including high levels of antioxidants and observations of the retardation of the cytopathological and biochemical defects known to result will be made. Further work on human lenses exposed to near-ultraviolet light in vitro will be done. Exposure of these lenses to near-UV light with varying levels of tryptophan in the culture medium will provide material to observe an increased pigmentation and fluorescence associated with the lens proteins, and alterations of their aggregation and charge properties. Continued efforts to learn the biochemical basis for the inhibition of ocular tissue enzymes (cytochrome oxidase, ATP-ase) in lens and retina by near-UV light and photoproducts will be made. The mechanism of action of such photoproducts in cell growth inhibition will be further studied. BIBLIOGRAPHIC REFERENCES: The Response of Mouse Ocular Tissues to Continuous Near-UV Light Exposure. S. Zigman, J. Groff, T. Yulo, and T. Vaughan: Invest. Ophthal. 14, page 709-713, September, 1975. Ocular Hazards of Potential Uses of Near Ultraviolet Light: S. Zigman, Eye, Ear, Nose and Throat - pages 1-4, March, 1976.